P53 is an evolutionarily conserved transcription factor with origins that can be traced back to the early metazoans, approximately 700 million years ago [1]. This transcription factor plays a critical role in regulating many fundamental aspects of reversible and irreversible cellular stress responses, genome surveillance, and suppression of oncogenic transformation [1]. In response to strong cellular stresses such as DNA damage or oncogenic signals, p53 regulates the expression of a large cohort of genes that affect cell-cycle arrest, senescence, and apoptosis [1]. Recent work has uncovered additional roles for p53 under basal physiological conditions. These include regulation of development, reproduction, metabolism, and self-renewal capacity [2], [3], [4], [5]. The factors that influence the diversity and duration of p53 responses are not well understood.